This invention relates to a system and method for cooling a battery pack and more particularly, to a system and method for cooling a battery pack within an electric or a hybrid electric vehicle and which includes a plurality of cooling passages which are internal to the battery pack and which provide for a substantially even rate of cooling throughout the battery pack, thereby reducing thermal gradients within the battery pack.
In order to reduce automotive emissions and the demand for fossil fuel, automotive vehicles have been designed which are powered by electrical devices such as batteries. These electric vehicles reduce emissions and the demand for conventional fossil fuels by eliminating the internal combustion engine (e.g., in completely electric vehicles) or by operating the engine at only its most efficient/preferred operating points (e.g., within hybrid electric vehicles).
In order to ensure optimal operation of these battery powered vehicles, it is necessary to provide cooling to the batteries in order to keep them at or below a certain temperature. The batteries in these vehicles are typically arranged within a pack containing several batteries or battery modules. Particularly, the battery pack will typically include several batteries disposed in rows and columns.
Prior cooling systems utilize a fan or blower to cool a battery pack. Particularly, the fan or blower directs pre-cooled air onto the battery pack, thereby cooling the individual battery modules. This type of cooling system, however, does not efficiently nor evenly cool the batteries, due to the fact that each of the individual batteries are disposed at different distances from the fan. As a result, this type of prior system often give rises to thermal gradients across the battery packs which adversely effect the performance of the batteries. Other types of prior systems which use liquid cooling arrangements are relatively expensive and undesirably and significantly raise the cost of the vehicle.
There is therefore a need for a new and improved battery cooling system and method which substantially provides for relatively rapid and even cooling throughout a battery pack.
A first non-limiting advantage of the present invention is that it provides a battery cooling system and method that efficiently and evenly cools several battery modules arranged in a pack.
A second non-limiting advantage of the present invention is that it utilizes a cooling mechanism or reaction which is internal to a battery pack, thereby providing for relatively rapid and even cooling throughout the battery pack.
According to a first aspect of the present invention, a system is provided for cooling a battery pack of the type used within a vehicle. The system includes a source of refrigerant gas; a pump for compressing the refrigerant gas; a high pressure conduit system which is fluidly coupled to the pump and which delivers the compressed refrigerant gas to the battery pack; at least one expansion valve which is fluidly coupled to the high pressure conduit system, and which is effective to decompress the refrigerant gas; and a low pressure conduit system which is fluidly coupled to the at least one expansion valve, which receives the decompressed refrigerant gas, and which circulates the refrigerant gas throughout the battery pack, thereby relatively rapidly and cooling the battery pack.
According to a second aspect of the present invention, a method is provided for cooling a battery pack of the type including a plurality of battery modules. The method includes the steps of compressing refrigerant gas; delivering the compressed refrigerant gas to the battery pack; decompressing the refrigerant gas; and channeling the decompressed refrigerant gas throughout the battery pack, thereby relatively rapidly and evenly cooling the plurality of battery modules.
These and other features, aspects, and advantages of the invention will become apparent by reading the following specification and by reference to the following drawings.